For various applications including, but not limited to, inductively coupled plasma (ICP) emission or mass spectrometry, it is beneficial to humidify gas streams. Bubbling-type humidifiers with a single reservoir can be used to humidify a flow of dry gas, which can be divided into two or more streams after humidification. To accurately control flow rate, the wet (humidified) gas must pass through a control device (e.g., gas flow controller). A drawback to this approach is that the wet gas can cause corrosion or instability of the control device due to condensation. Additionally, a bubbling-type humidifier with a single reservoir is not able to simultaneously humidify two different gas streams having different chemical composition.